Integrating custom OpenGL with QQuickFramebufferObject

[Tom asso]

I’d like to integrate my “custom” OpenGL drawing into QML via the QQuickFrameBufferObject approach described here. But I don't understand what Renderer::createFrameBufferObject() is supposed to return, given my current renderer. My custom renderer already maintains a VAO and three FBOs for vertices/colors, normals, and triangle-drawing indices:

/// Vertex Array Object, holds all information to render surfac
QOpenGLVertexArrayObject *m_vao;

/// Vertex buffer object holds surface vertex positions and colors
QOpenGLBuffer *m_positionColorBuffer;

/// Vertex buffer object holds surface normal vectors
QOpenGLBuffer *m_normalBuffer;

/// Index buffer object holds indices for triangle strips
QOpenGLBuffer *m_indicesBuffer;

My renderer initializes these:

m_vao->create();
m_vao->bind();
m_positionColorBuffer->create();
m_positionColorBuffer->bind();
m_positionColorBuffer->allocate(position-colors data here);

m_normalBuffer->create();
m_normalBuffer->bind();
m_normalBuffer->allocate(normal vectors here);

m_indicesBuffer->create();
m_indicesBuffer->bind();
m_indicesBuffer->allocate(index-drawing list here);
// compile shaders, set attribute buffers, etc.

My renderer's render method does this:

m_vao->bind();
glDrawElements(GL_TRIANGLES, m_indicesCount, GL_UNSIGNED_INT, 0)
m_vao->release();

But the example shows return of a single QOpenGLFrameBufferObject:

class FbItemRenderer : public QQuickFramebufferObject::Renderer
{
    QOpenGLFramebufferObject *createFramebufferObject(const QSize &size)
    {
        QOpenGLFramebufferObjectFormat format;
        format.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
        // optionally enable multisampling by doing format.setSamples(4);
        return new QOpenGLFramebufferObject(size, format);
    }

So in my renderer's case, what should createFrameBufferObject() return?
Thanks!